I have a 1999 ranger that the fuel gauge has been reading empty. I just replaced the entire fuel pump hanger assembly and now the gauge reads way past full. Not sure if the float might be hung up on something or if something else might be the issue.

 

Welcome to the forum

Was the Float on the old assembly bad?
Full of gasoline so it sank to bottom of tank, no longer a "float", lol, that makes the gauge show EMPTY all the time.

Gauge will show past full if connector on tank is not plugged in tight

 

I checked the float on the old when when I pulled it and it wasn’t full. Guess I’ll be moving the bed again and checking the connections

 

Have an OHM Meter handy
Set it to 200ohms, if it has OHM settings
Ohms readings do not require power, so key off with all ohm tests
On the connector on the tank will be yellow/white stripe wire, that wire runs to the gas gauge/cluster
And a Black/white or black/orange wire, that's the ground wire for the float/sender unit
Unplug the connector
Put ohm meter on those two connections for the sender in the tank, there is no polarity, black or red, either way will show ohms
You should see between 16 and 158 ohms depending on gas level in the tank
16 ohms in EMPTY
158 ohms is FULL
Rock the truck a bit and you should see ohms change as gas in the tank sloshes around and float goes up and down
If this happens then sender in the tank is fine
Hook connector back up and turn on the key
If connection is OK you should see correct level on the gauge

If not you will need to pull out the instrument cluster and test the yellow/white wire at that end, I would leave the bed off for now

On the back of the cluster are 3 connectors, 16 pin, 12 pin and 10 pin
Yellow/white wire is on the 12 pin connector, and pin 12, end of connector
Assuming all 3 connectors are unplugged
Use Ohm Meter again put one probe on yellow/white wire and other probe on a cab ground, bolt head or ??, any unpainted metal
Should see the same ohms as before, 16-158 ohms, if so yellow/white wire is OK

Rangers have a separate circuit board on the back of the cluster, called the anti-slosh module, it can be pulled out
These do fail and can cause always empty or always full on gauge

Google: Ranger anti-slosh module

Lots of things you can try
Replacements are Year specific, not a "one size fits all" module